1) 1/(x1+x2)=10 1/(x2+x3)=15 1/(x1+x3)=18
2)x1+x2 = 1/10 => x1 = 1/10-x2
3)x2+x3 = 1/15 => x3 = 1/15-x2
4)1/(1/10-x2+1/15-x2)=18
5)1/10+1/15-2*x2 = 1/18
6)5/30-2*x2=1/18 ; 5/30 = 1/6
7)2*x2=1/6-1/18
8)2*x2= 2/18
9)x2= 1/18
10)x1 = 1/10-1/18 = 2/45
11)x3 = 1/15-1/18 = 1/90
12)1/(x1+x2+x3) = 1/(1/18+2/45+1/90) = 9 минут
<span>5(m-2n) + 2(5n-m)
5m-10n+10n-2m
3m</span>
73-х=4*16
73-х=64
-х=64-73
-х=-9
х=9
А)(6-5а)(6+5а)
б)(3х-2а)(3х+2а)
в)(1-4b)(1+4b)
г)(7а-10)(7а+10)
Смотри ниже, в центре будет заветная C